GB2145800A

GB2145800A - Damper disc assembly

Info

Publication number: GB2145800A
Application number: GB08421212A
Authority: GB
Inventors: Hiroshi Takeuchi
Original assignee: Exedy Corp; Daikin Manufacturing Co Ltd
Current assignee: Exedy Corp
Priority date: 1983-08-29
Filing date: 1984-08-21
Publication date: 1985-04-03
Also published as: DE3431765C2; US4563165A; GB8421212D0; JPS6049125A; FR2551152B1; FR2551152A1; GB2145800B; DE3431765A1

Description

1 GB 2 145 800A 1

SPECIFICATION

Damper disc assembly This invention relates to a damper disc as- sembly suitable for an automobile clutch disc.

A damper disc having multi-stage rigidity and multi-stage hysteresis torque character istics has conventionally been known wherein an outward flange formed integrally with a hub is divided into two, namely an outer portion and an inner portion. Sub-side plates in addition to annular side plates are fitted onto the hub and they are elastically inter connected by various kinds of torsion springs, so that a twist angle 0/twist torque T charac teristic as shown in Fig. 1 is provided in the damper disc.

In a damper disc having the characteristic shown in Fig. 1, the torsional rigidity changes 85 in three steps and at the same time the hysteresis torque changes in two steps in the course of the damper twisting from its neutral state to its maximum twisted state. Here, a torsional vibration of low torque is absorbed in 90 a low twist angle region (0 to 0,) so that the torsional rigidity is set to a low value and the hysteresis torque is also set to a low value.

For this reason, when the damper disc is employed in a clutch disc for a vehicle, for 95 example, this characteristic in the small twist angle region is effective as a counter-measure against noise at a low rotational speed such as an idling, but conversely it has the disadvan tage of inducing or enhancing oscillation of the vehicle body when the gear is on the verge of moving, i.e. when the accelerator pedal is slightly pushed in or released quickly.

In consideration of the above disadvantage, an object of this invention is to provide a damper disc wherein the hysteresis path is directly shifted to a second-stage rigidity re gion at a negative side at a high rotational speed without permitting it to pass through a first-stage rigidity region having low twist tor- 110 que/low hysteresis torque characteristics when returning from a large twist angle re gion, so that torque fluctuation can be readily absorbed without inducing or enhancing dis advantages such as oscillation of the vehicle body, etc. even when violet fluctuation is generated when the gear is on the verge of moving.

In order to accomplish the above object this invention proposes a damper disc assembly wherein an outwardly projecting flange of a hub is divided into an inner portion and an outer portion, an outward toothing of the inner portion meshing withan inward toothing of the outer portion with a radial clearance therebetween, the inner portion and the outer portion of the flange also being elastically inter-connected by a weak first torsion spring extending in a circumferential direction, side plates being located on each side of the 130 flange and being elastically interconnected to the outer flange portion by a strong second torsion spring extending in the circumferential direction, characterized in that a locking mem- ber is provided which enters the clearance between the outward toothing and the inward toothing under the influence of a centrifugal force generated by rotation of the damper disc assembly, and a spring mechanism is pro- vided to urge the locking member out of said clearance, the rigidity of the spring mechanism being chosen so that the rigidity overcomes the centrifugal force at a low rotation speed and the centrifugal force overcomes the rigidity at a high rotational speed.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which:- Figure 1 is a graph showing twist angle/twist torque characteristics of conventional disc assemblies and of the disc assembly of the present invention in some instances; Figure 2 is a vertical cross-section of one embodiment of the damper disc assembly according to the present invention employed in a clutch disc for an automobile; Figure 3 is a partial cross-section taken on the line 111-111 of-Fig. 2; Figure 4 is a partial cross-section taken on the line IV-IV of Fig. 3; and Figure 5 is another graph showing twist angle/twist torque characteristics of a disc assembly in accordance with the present invention in certain circumstances.

Fig. 2 is a vertical cross-section of a preferred embodiment of the damper disc according to the present invention as employed in a clutch disc for an automobile. This corre- sponds to a sectional view taken on the line 11-11 of Fig. 3, which is the partial sectional view taken on the line 111-111 of Fig. 2. Further, Fig. 4 is a partial sectional view taken on the line IV-IV of Fig. 3. Here, an arrow F indicates the forward side.

In Fig. 2, a spline hub 1 is fitted onto a horizontal output side clutch shaft (not shown) by means of an internal spline 2, and has an inner flange portion 3 integral therewith. An outer flange portion 4 is disposed on the same vertical plane outwardly of the inner flange portion 3, and an external tooth 5 provided at an outer periphery of the inner flange portion 3 meshes in a freely rotatable manner withan internal tooth 6 on the outer flange portion 4 with radially arranged clearances 7, 7' left therebetween, as shown in Fig. 3. Further, a pair of sub-plates 9, 9' are securely fixed to both front and rear side faces of the outer flange portion 4 by means of a sub-pin 8. The sub-plates, 9, 9' are parts made by plate work having radial sector projections 9a and their inner edges slidingly abut an outer surface of the hub 1 to support the outer flange portion 4 concentrically with 2 GB 2 145 800A 2 the hub 1. A friction material 10 is interposed between the inner portions of the sub-plates 9, 9' and the inner flange portion 3. First torsion springs 12 (first-stage springs) are compressively installed in two recesses 11 provided on an outer part of the inner flange portion 3 with their centre lines extending generally circumferentially of the disc. The respective end portions of a washer 14 (Fif. 4) fit into notches 13 provided on the sub-plates 9, 91.

As shown in Fig. 2, a retaining plate 17 and a clutch plate 18 are disposed on the outer sides of the sub-plates 9, 9', opposite to the inner flange portion 3, with friction washers 16 disposed therebetween and outer portions of both plates 17, 18 are connected to each other by means of a stop pin 19. Second torsion springs 21 (second- stage springs) are compressively installed in two window holes 20 provided on the same circumference of the outer flange portion 4 with their centre lines extending generally circumferentially of the disc. Portions of each spring 21 project from its respective window hole 20 and fit into two window holes 22, 23 one provided in each plate 17 and 18. End faces of the respective window holes 20, 22, 23 when considered in circumferential direction, are aligned with each other at respective circum- ferential positions under a neutral state, and at this time bothends of eachspring 21 are pressed into contact with both end faces of the window holes 20, 22, 23.

Further window holes 24 (Fig. 4) are pro- 100 vided in two places on the same circumfer ence of the outer flange portion 4, and third torsion springs 25 (third-stage springs) are installed in the window holes 24 with their centre lines extending generally circumferenti- 105 ally of the disc. Portions of each spring 25 projects from its respective window hole 24 and fit into window holes 27, 28 one provided in each of plates 17 and 18, and each third spring 25 is pressed into contact with- both ends of the window holes 27, 28, when considered in the circumferential direction. The length of each window hole 24 is greater than the lengths of the respective 50 window holes 27, 28 in the disc's circumfer- 115 ential direction and consequently a radial clearance is formed between each window hole 24 and the respective spring 25 in the neutral state as shown in Fig. 3. 55 Incidentally, the stop pin 19 is disposed in a notch 29 provided on an outer part of the outer flange portion 4 with a considerable clearance the pin 19 and the notch edge in the circumferential direction.

A facing 32 is fastened to an outer portion of the clutch plate 18 by way of a cushioning plate 31. The facing 32 is disposed between a flywheel (not shown) at the side of an engine and a pressure plate at the side of a clutch case.

In the damper disc assembly according to the present invention, a locking member 33 is disposed between the outer flange portion 4 and the subplate 9, as illustrated in Fig. 2.

Although only one is shown in the figure, actually two locking members 33 of the same construction are disposed on the disc diametrically opposite each other. As shown in Fig. 3, a rotating part 34 of the locking member 33 is formed into an L-shaped made by plate work and its outer portion 34a extends in the circumferential direction to serve as a weight. A bent portion 34c is formed at the extreme end of the outer portion 34a to increase the weight thereof and this portion 34c covers the outer peripheral side or outer edge of the outer flange portion 4. A central part of the inner portion 34b of the rotating part 34 is mounted rotatably onto one pine 8a of the sub-pins 8. A pin 35 extending parallel to the axis of the disc is fixed to the inner end of the inner portion 34b. This pin 35 projects into a clearance between the inner flange portion 3 and the outer flange portion 4 is held in place by a roller 36 located between the flange portions 3 and 4, into which the pin 35 fits, as shown in Fig. 2. A flange 37 to prevent the roller 36 slipping off is integrally formed at the end of the pin 35. As shown in Fig. 3, a contacting surface of the externaltooth 5a is sloped in the vicinity of the pin 35 so as to mate with a track of the pin 35 having its centre at the pin 8a. Further, a notch 38 extending outwardly from an internal tooth 6a is formed on the outer flange portion 4, and a bottom surface of the notch 38 is formed into a circular-arc-shape having its centre at the pin 8a so as to mate with a track of the pin 35. A torsion spring 39 (an example of the spring mechanism) fits onto a pin 8b which forms a counterpart to the pin 8a. One end 39a of the spring 39 Hooks to one end of the notch 29 and the other end 39b compressively hooks to the outer portion 34a of the rotating part 34. Accordingly, the rotating part 34 is always urged in the direction of the arrow E (Fig. 3) by means of the spring 39.

Now, the function of the damper disc will be described hereunder. When a pressure plate (not shown) presses the facing 32 against a flywheel of an engine, a torque will be transmitted from the flywheel through the facing 32, the plate 3 1, the plate 18, the spring 2 1, the outer flange portion 4, the spring 12 (Fig. 3), the inner flange portion 3, and the hub 1 to an output shaft. The rotational direction of the disc is indicated by the arrow X, in Fig. 3.

When, for example, a twist torque is applied to the facing 32 in the direction of X, in relation to the spline hub 1, torque vibration will be absorbed in the following manner. The function will be described hereunder on the basis of Fig. 1 showing the twise angle 3 0/twist torque T characteristic.

In the case of the low rotational speed (First stage) When the facing 32 is twisted from a neutral state in the direction of X, in relation to the hub 1, the rigidity of the first torsion spring 12 is set greater than that of the second torsion spring 21 within a twist angle 0 from 0 to 0, so that the spring 21 functions like a rigid body to rotate the plate 18 integrally with the outer flange portion 4.

As a result, a torsion arises between the outer flange portion 4 and the inner flange portion 3, the spring 12 is compressed by means of the sub-plates 9, 9' and at the same time slippage occurs on a surface of the friction material 10 to cause a slight friction torque, thus a relationship A as shown in Fig. 1 is obtained. Since the rotational speed is low (under an idling condition, for instance), the centrifugal force acting on the outer portion 34a of the locking member 33 is small and the pin 35 does not fit in between the teeth 5a, 6a due to the spring 39 being kept disengaged therefrom as shown in Fig. 3.

(Second stage) When the spring 12 is com pressed to cause each end face of the internal tooth 5 and the external tooth 6 to contact each other, the torsion between the inner flange portion 3 and the outer flange portion 4 will not increase. Accordingly, the outer flange portion 4 twists against the plate 18 within a twist angle 0 from 0, to 02, the spring 21 is compressed and at the same time slippage occurs on a surface of a washer 16 to cause a friction torque so that the relation ship B as shown in Fig. 1 is obtained.

Twisting of the plate 18 against the outer flange portion 4 minimizes the radial clear ance between the outer flange portion 4 and the spring 25 of Fig. 3, and finally the twist angle 0 reaches 02 when the clearance be comes zero.

(Third stage) Both the second and third springs 21, 25 are compressed within a twist angle 0 from 02 to 0., thus the relationship C shown in Fig. 1 is obtained. When the twist angle 0 reaches 0, the stop pine 19 contacts an end face of the notch 29 and the plate 18 becomes integrated with the outer flange por tion 4 by way of the stop pin 19 so the torque is transmitted directly to the hub 1.

(stage returning from max. twist angle 0J When the above actuation is reversed relation ships C', B' and A' are obtained owing to friction of the friction material 10 and the washer 16. Incidentally, the hysteresis ob tained by the friction of the friction material is set to an extremely small value in the first stage (0 - 0j, so that A and A' are 125 shown by the same straight line.

In the case of high rotational speed (First stage) As in the case of low rotational speed, the first torsion spring 12 is corn- 130 GB 2 145 800A 3 pressed first and the outer flange portion 4 rotates in the direction of X, in relation to the inner flange portion 3, so the clearance between the external tooth 5a and the internal tooth 6a increases. Since the rotational speed is high (vehicle running condition, for instance) the outerportion 34a of the rotating part 34 overcomes the torsion spring 39 with the aid of its centrifugal force to move circum- ferentially and outwardly. As the result, the rotating part 34 rotates around the pin 8a in the direction opposite the arrow E and the pin 35 onto which the roller is fitted engages in between the external tooth 5a and the internal tooth 6a. The engagement of the pin 35 causes the inner flange peripheral portion 3 to be integrated with the outer flange portion 4 with the spring 12 kept compressed as it is.

(Second & third stages) The actuation is the same as that in the case of low rotational speed.

(Stage returning from max. twist angle 03) In this stage the pin 35 of the locking member 33 engages in between the external tooth 5a and the internal tooth 6a to cause the inner flange portion 3 to be integrally connected to the outer flange portion 4, so that first stage actuation accompanied by compression of the first torsion spring 12 does not occur. Accordingly, the disc presents a characteristic having no low hysteresis torque region (first stage) as indicated in Fig. 5.

Incidentally, when the rotational speed lowers from the above stage, the spring 39 overcomes the centrifugal force to rotate the rotating parts 34 in the direction of E and pull the pin 35 out from between the teeth 5a, 6a, so that the characteristic will automatically returns to that of Fig. 1. Furthermore, when twisting the disc from the neutral state in the direction opposite to E, the clearance between the teeth 5a, 6a is closed when twisting occurs between the inner flange portion 3 and the outer flange portion 4, so that there is no chance of the inner flange portion 4 and the outer flange portion 3 being locked regardless of the rotational speed. Consequently, the characteristic of Fig. 1 can always be obtained independently of the rotational speed.

As mentioned above, according to this invention the damper disc assembly has the outward flange of the hub 1 divided into the inner portion 3 and the outer portion 4 and the inward tooth 6 of the outer flange portion 4 is meshed with the outward tooth 5 of the inner flange portion 3 with a radial clearance left therebetween and at the same time the inner portion 3 and the outer portion 4 of the flange are elastically connected to each other through the weak first torsion spring 12 extending in the circumferential direction. The side plates (for example, the clutch plate 18 and the retaining plate 17) are disposed on both sides of the flange and at the same time the outer flange portion 4 is elastically inter- 4 GB 2 145 800A 4 connected to the side plates through the strong torsion spring 21 extending in the circumferential direction. The locking member 33 is provided which enters the clearance between the outward tooth 5 and the inward 70 tooth 6 because of the centrifugal force gener ated by rotation of the damper disc assembly.

The spring mechanism (for example, the re turn spring 29) is provided to urge the locking member 33 out of the clearance and the rigidity of the spring mechanism is determined to the extent that the rigidity overcomes the centrifugal force at low rotational speed and the centrifugal force overcomes the rigidity at high rotational speed so that the twist angle 0/twist torque T characteristic can be ob tained wherein the hysteresis path is directly shifted to the second-stage rigidity region at the negative side at high rotational speed without permitting it to pass through the first- 85 stage rigidity region having the low twist torque, low hysteresis torque characteristic when returning from the large twist angle region. Therefore, when this damper disc is for example, employed in the clutchdisc for a vehicle, the present invention has the advan tage that the torque fluctuation can be readily absorbed without inducing or enhancing dis advantages such as oscillation of vehicle body, etc. even during violent fluctuations at 95 the time when tip-in/tip-out is generated (when the accelerator pedal is raised or de pressed quickly yet slightly).

The invention is not confined to the precise details mentioned above and the following 100 variations, in particular, are possible within the scope of the claims.

Firstly the locking member 33 and the spring mechanism may be disposed between the outer flange portion 4 and the sub-plate 9,' or they may be disposed on both sides of the outer flange portion 4. Secondly, a part of the plurally provided locking member 33 and the spring mechanism may also be disposed on the side, between the outward tooth 5 and the inward tooth 6, where the clearance is widened when the facing twists in the direc tion opposite to X, in relation to the hub 1.

Thereby, in the event when the disc twists in the direction opposite to Xl, the characteristic not passing through the first-stage rigidity region, as in Fig. 5, can be obtained. Finally, springs 21, 21 and 25 in the form of coil spring are not necessarily required. Instead a rubber-like elastic body may be used in each location.

Claims

1. A damper disc assembly wherein an outwardly projecting flange of a hub is div ided into an inner portion and an outer por tion, an outward toothing of the inner portion meshing with an inward toothing of the outer portion with a radial clearance therebetween, the inner portion and the outer portion of the flange also being elastically interconnected by a weak first torsion spring extending in a circumferential direction, side plates being located on each side of the flange and being elasticallyinterconnected to the outer flange portion by a strong second torsion spring extending in the circumferential direction, characterized in that a locking member is provided which enters the clearance between the outward toothing and the inward toothing under the influence of a centrifugal force generated by rotation of the damper disc assembly, and a spring mechanism is provided to urge the locking member out of said clearance, the rigidity of the spring mechanism being chosen so that the rigidity overcomes the centrifugal force at a low rotation speed and the centrifugal force overcomes the rigidity at a high rotational speed.

2. A damper disc assembly as claimed in claim 1 in which the locking member comprises an approximately L-shaped rotating part, an outer portion of which extends in the circumferential direction to serve as a weight and an inner portion of which is fixed to a pin lying parallel to the disc axis, a roller fitted onto the pin being cpable of entering the clearance between the outward toothing and the inward toothing.

3. A damper disc assembly as claimed in claim 2 in which a bent portion is formed on the outer portion of said rotating part, which bent portion covers an outer peripheral side of the outer flange portion.

4. A damper disc assembly as claimed in claim 2 or 3, which the spring mechanism comprises a torsion spring fitted on to a pin provided on the outer flange portion, one end of the torsion spring being compressively hooked to the outer portion of the rotating part of the locking member.

5. A damper disc assembly as claimed in claim 4 in which a stop pin is provided between the side plates, the stop pin being located in a notch provided on the outer flange portion with a clearance remaining between the stop pin and the notch, and in which the other end of the torsion spring hooks to the notch.

Printed in the United Kingdom for He, Majesty's Stationery Office. Dd 8818935, 1985, 4235Published at The Patent Office, 25 Southampton Buildings. London, WC2A 1 AY, from which copies may be obtained-